IPA: /nɒnədˈmɪʃən/
KK: /nɑnədˈmɪʃən/
Not allowed to enter or be accepted.
The nonadmission of students to the program caused disappointment.
Nonadmission → It is formed from "non-" (meaning not) and "admittere" (meaning to allow to enter). The word "nonadmission" refers to the state of not being allowed to enter or not being admitted.
Think of 'not' ('non-') allowing someone to 'enter' ('admittere') — that's why nonadmission means not being allowed to enter.